Counterflow liquid-granular material transfer process and apparatus

ABSTRACT

In the closed cycle, mobile bed, liquid-solid treatment installation disclosed herein, a given volume of the solid material is periodically displaced in the treatment chamber by a given volume of liquid under a given pressure.

United States Patent Claude Blain Palsaiseau;

Paul Minart, Grenoble; Roger Platzer, Chattillon-Sous-Bagneux; Pierre Pouchot,

[72] Inventors Lancey, all of France [21] Appl. No. 9,846 [22] Filed Feb. 9, 1970 [23] Division of Ser. No. 639,777,

May 19, 1967, abandoned. [45] Patented Nov. 9, 1971 [73] Assignees Commissariat A LEnergie Atomique (C.E.A.) Paris, France; Societe Grenobloise DEtudes Et DApplications Hydrauliques Grenoble, France [32] Priority May 20, 1966 [3 3 France [3 l 4940 [54] COUNTERFLOW LlQUlD-GRANULAR MATERIAL TRANSFER PROCESS AND APPARATUS 6 Claims, 2 Drawing Figs.

[52] US. Cl 210/33, 210/138, 210/189, 210/258 [51] lnLCl BONUS/02 801d 33/16 [50] Field of Search 210/33,

[56] References Cited UNITED STATES PATENTS 2,693,395 11/1954 Berg 210/33 X 2.815,322 12/1957 Higgins 210/33 3,056,743 10/1962 Eichhorn et a1. 210/33 3,272,335 9/1966 Nettel 210/262 X 3,298,950 1/1967 Mindler..... 210/33 3,503,510 3/1970 Minart et a1. 210/189 Primary Examiner-Samih N. Zaharna ArlorneysSylvester .1. Liddy, John .1. Hart, Joe E. Daniels and Charles E. Baxley ABSTRACT: In the closed cycle, mobile bed, liquid-solid treatment installation disclosed herein, a given volume of the solid material is periodically displaced in the treatment chamber by a given volume ofliquid under a given pressure.

PATENTEnunv 9 law BYROGER PIATZER PIERRE POUCHQT Arron/5) COUNTERFLOW LIQUID-GRANULAR MATERIAL TRANSFER PROCESS AND APPARATUS This is a division of application Ser. No. 639,777, filed May 19, 1967 and now abandoned. THE INVENTION This invention relates to a solid-liquid treatment installation in which a mobile bed moves in the direction of liquid flow for a few seconds at a time according to a recurrent cycle, and remains stationary with respect to the treatment column containing it during periods of reverse flow treatment. The installation may or may not be of the closed cycle tape and if of such type may include more than one treatment column.

. in mobile bed installations, it is nearly always necessary to know the hourly rate of volume flow and to adjust it as accurately as possible. Adjustment of the frequency of thebed movements is a simple matter with the aid of a timing device, but accurate determination and control of the volume of matter transferred at each movement is more difficult to achieve. In the arrangements which have been proposed to date, the displacement of the material is brought about by injection of a liquid under pressure for a set time, see for example US. Pat. No. 2,815,322, dated Dec. 3, 1957. It has been found that with this method, it is not possible to obtain an amplitude of displacement that can be reproduced in time. This is why installations operating by this principle feature volume measurement tanks which are distinct from the actual treatment columns, being isolated from them and from the source of material by valves, and which are filled right up without there being a liquid layer above the material. Consequently, the filler duct from the source of material also remains full of material, so that some crushing of grains of material in the inlet valve when it closes cannot be avoided. The inlet valve has been eliminated in certain of these installations to avoid the crushing problem, but when the volumetric measurement tank empties into the column, the filler duct also does'so at least partly, due to continuity, so that the exact volume which has emptied cannot be established. Experience has also shown that the use of a volumetric measurement tank for granular material is debatable in any case. It is known that the bulk volument of a given mass of granular material in a liquid depends on such difierent factors as grain size, roughness and shape, interstitial fluid properties and such outside factors as vibration, settling, typeof wall, etc. Because of all these factors the results obtained by material volume measurement are at to be anything but consistent over a period of time. In this connection, itmight be stated that it has been found that the most important thing in a mobile bed treatment installation designed for continuous operation, is to achieve a constant rate of solid material flow. The need to keep this flow constant is more important than any ability to determine its value with the aid of a separate measurement tank, for not only is such measurement inaccurate, but the volume emptying out will not necessarily be the same as the volume of material displaced in the column while it is emptying, whether the latter be located before or after the measurement tank.

Further, in certain of the mobile bed installations, some of the operations take place in separate columns operating simultaneously, each column beingdescribed for a specific form of treatment. The solid material circulates through the installation in a closedcycle, passing through each column in turn, but in view of the specific nature of each treatment, it is necessary to isolate the individual columns from each other while providing means to allow the granular material to be transferred periodically from one to the other. At this point, it is desired to distinguish what is here-termed a mobile bed. installation from the type of installation in which'all of the solid material is emptied out of one column after treatment and is then sent to another one for further treatment. Such installations are related to mobile bed installations by the fact that each individual treatment takes place within an appropriate vessel tank or receiver and that the solid material passes from each such vessel tank or receiver in turn to the next one, but they really operate as fixed-bed installations because there are no opposite flows of fluid and solid material in their columns to ensure a methodical transfer process.

It is known that the transfer of material in a mobile bed installation involves a certain number of problems, one of the most important of which is now to get the isolation valves or other devices to close to give a perfect seal without crushing any of the solid material. All known installations of this type characteristically have opposite flows and there is always at least one valve or cock closing against the flow of the solid material, because in order to be able to permanently isolate two successive columns in the solid material circuit, at least two valves or cocks are required in series, one of them being closed when the other is open, and vice versa, and with an intemiediate receiver between them; Consequently, when such a receiver is used as a means of measuring volumes of material, some material invariably gets crushed whenever the inlet valve closes. If the measurement tank only features an emptying valve, this must also serve as an'inl'et valve for a further intennediate receiver, vessel or tank following the measurement tank and separated from the next column by a valve or cock closing against a flow of resin. Though one could, if really necessary, arrange to keep the measurement tank emptying valve open for the time required to ensure that it does not close until all the material has emptied out, the same does not apply for the intermediate receiver, which still contains some solid material when the valve between it and the next column closes.

The primary purpose of the present invention is to provide a mobile bed installation which does not have the above described disadvantages.

One of the objects of the invention is to provide an improved mobile bed treatment installation'having a constant accurate rate of solid material flow. In accordance with the invention this object is accomplished by periodically displacing the granular material bed in a treatment column with the injection of a preset volume of liquid under a given pressure into such column.

Other objects of the invention, as well as the advantages thereof, will become apparent from a perusal of the following description when read in connection with the accompanying drawings in which FIG. 1 is a diagrammatic view showing by way of example one possible form of an installation embodying the features of the invention; and

FIG. 2 is a diagram illustrating the sequence of operations in the installation of FIG. 1.

The installation shown in the drawings is of the type that may be utilized for treatment of a solution by the solid particles of a closed-circuit ion exchanger. Such an installation may comprise an elution and washing column, generally designated 2, of smaller diameter than the fixing column. The column 2 basically consists of a cylindrical body 20 and a base or housing 21 surrounding the bottom portion of the body 20; The bed 20' of exchange resins filling the column 20 is over a sand bed 23 having an outlet strainer 24 buried in the same and connected to an outlet duct provided with a valve 24a. The operation of valve 24a may be'controlled by a suitable timer generally designated 10 andof a type known to the art.

The body 20 of the elution and washing column 2 may have connected to its upper end a liquid outlet pipe provided with a suitable valve. A short distance below the entry end of the liquid outlet pipe, the column body 20 may have connected thereto one end' of a resin discharge pipe that runs off at an angle of 45 downwardly and provides a spill for the resins of the bed 20". The resin discharge pipe may abo be'provided with a control valve edjacently to'the column 20. Located in short distance below the entry end of the rcsindlscharge pipe, the column body 20 may be further provided-wltha peripheral annulus or strainer which is connected by a pipe provided with a valve to a suitable source for the washing solution that is fed therefrom into the top of the bed 20. A little further below such annulus the column body 20 may be provided with a second peripheral annulus or strainer that is connected to a suitable source for the eluant feed through a'pipe provided with a valve.

The exchange resins in the bed 20' are supplied from a storage tank 43, which discharges by gravity through a downwardly inclined pipe 44 into the annular chamber 22 where the resins form a heap which gradually grows in height until it blocks the discharge end of the pie 44 and thereby cuts off the feed from such pipe. The discharge end of the pipe 44 is located at a given level which determines the maximum level of the heap of resins in the chamber 22 and leaves a space in the upper portion of such chamber for the fluid which is to impel the resins periodically from such chamber into the bed 20' through the annular opening between the bottom end of the body 20 and sand bed 23 in the manner described in greater detail in U.S. Pat. No. 3,503,510, dated Mar. 3, 1970 for Installation for Treating Liquids and Granular Solids.

The impelling liquid for delivering the resins to the bed 20' consequently for imparting periodic forward motion to such solid material bed, is delivered tangentially into the upper portion of the annular chamber 22 through a duct or pipe 45 controlled by a valve 45a. The pipe 45 is connected through a valve 62 to a suitable source of such liquid in a known manner. The bottom end of a tank 58 is also connected to pipe 45 at a place located between the valves 45a and 62. The volume of impelling fluid supplied to the tank 58 from the pipe 45 is determined by the space between two electrodes 56, 57 positioned in the tank and forming part of known means for controlling the operations of the valves associated with such tank. A vent valve 63 is connected to the top end of the tank 58 and is open to relieve the pressure in the upper portion of the tank while the tank is being filled with the impelling fluid. The space in the tank 58 above the impelling fluid therein is supplied with compressed air from a duct 59 though a pressure reducer 60 and an isolation valve 61.

As is shown in FIG. 1, the valves 61, 62, 63 and 45a are connected to the timer 10. The electrode 57 is in a line which contains the timer and valves 61 and 45a. The electrode 56 is in a line which contains the valves 63 and 62. The arrangement is such that when the tank 58 is to be filled with impelling liquid, valves 62 and 63 are opened by the timer, all other valves being closed. When the liquid in the tank 58 reaches the electrode 56, the tank is filled at the preset volume and electrode 56 operates to cause the closing of valves 62 and 63. When the timer operates to efi'ect the injection of the preset volume of impelling liquid under a given pressure into the chamber 22, valves 61 and 450 are opened by the timer. When the liquid in the tank 58 drops to electrode 57, the preset volume thereof has been injected and electrode 57 closes valves 61 and 45a.

It will be understood from the foregoing description of the means for injecting an impulse of impelling liquid into the annular chamber 22, that during the treatment period that takes place in column 2 between two of such impulses the impelling liquid will be fed by the duct 45 into the tank 58. While such feed takes place, the vent valve 63 will be open, the feed valve 45a closed, and the treatment valve 24a open. The filling of tank 58 ceases when the liquid level reaches the upper electrode 56 which causes the closing of the vent valve 63. When an impulse of the impelling liquid is to be delivered from tank 58, feed valve 45a is opened and valves 24a and 62 are closed. Compressed air is then fed through the duct 59, the pressure reducer 60 which holds the air at a constant pressure, and the valve 61 to the tank 58 to expel the liquid therein into the duct 45 and through valve 45a tangentially into the upper portion of the annular chamber 22. This discharge of the liquid from the tank 58 will be maintained until the liquid level therein falls just below the lower electrode 57 which causes the closing of valve 61. At least one of the electrodes 56, 57 should preferably be adjustable for height to enable setting the amount of the impelling liquid volume in accordance with requirements. It is important that the time between the opening and closing of valve 45a be sufficient to enable all of the liquid between the two electrodes 56 and 57 to be expelled into the annular chamber 22.

The timing of the operations of the aforesaid parts for injecting a given volume of the impelling liquid into the annular chamber 22 can be best understood, it is believed, from a consideration of FIG. 2 of the drawings. In the diagram shown in FIG. 2, the different operations are shown on the ordinate 0V and the time periods for such operations on the abscissae"OT,.

On the horizontal line designated I are plotted the treatment periods T in the column 20, which periods are separated by time periods 1 during which take place the aforesaid impulse operations i.e., the periods during which the liquid in the tank 58 is expelled through the duct 45 and valve 45a into the annular chamber 22. The timing of these impulse operations, which are designated E, are shown on line III of FIG. 2. The points 2 on line 1 indicate when the valves 45a and 24a open and close, respectively, with relation to the treatment periods T, and the point r, on line 1, indicates when such valves 24a and 45a, open and close, respectively, with relation to such treatment periods. The filling operations of tank 58 are indicated at F on line 11.

It is believed that the diagram shown in FIG. 2 clearly points out that the time I selected for the impulse operations is such that this operation is carried out in its entirety before the closure of the feed valve 45a, i.e., before the beginning of a treatment in column 20. As has been previously indicated, during this injection of a preset volume of the impelling liquid under a given pressure into the annular chamber 22, a given displacement of the granular material bed in column 20 will take place. During this displacement, a certain amount of slip of the liquid takes place with respect to the grains of material. It is accordingly necessary in order to displace a given volume of the granular material, to inject a greater volume of liquid than that of the material to be displaced. It will also be appreciated that displacement of the granular material should preferably occur within a few seconds in order that the bed may progress up the column 20 as a piston with minimum loss through compaction. This it has been found can be achieved by a proper selection of the impelling pressure of the liquid i.e., by proper control of the pressure of the compressed air entering the tank 58.

It will be understood from what has heretofore been said that resin displacement will occur intermittently in the column 2. During the treatment periods the resin bed in column 2 will be stationary. In a treatment period the valves controlling the feed of the washing solution and the eluant to column 2 and the latters outlet valve 240 are open and the elution and washing process will take place. As has been previously indicated the rate of resin flow is regulated in the elution and washing column 2. At a set frequency controlled by the timing device 10 in a manner known in the art, the aforesaid eluant and washing feed valves and the outlet valve 24a close, the liquid outlet valve associated with the upper end of column 2 and valve 450 open, and a predetermined volume of liquid under pressure, referred to as the impulsion volume, is injected into the annular chamber 22 in the base of column 2 in the manner previously described. Simultaneously, an identical volume of liquid will discharge from the top of column 2 through the outlet pipe. Such impulsion volume of liquid will depress the resin level in the annular chamber 22 and cause the bed 20' in column 2 to move upwardly as a piston for a few seconds, the resin feeding from the chamber 22 in a circumferential manner inwardly through the circular opening at the lower end of the column body 20 and into the body of the bed in a manner described more in detail in said U.S. the elution No. 3,503,510. Following the upward step of bed 20', the elution and washing processes are resumed and the spill valve opens to let the resin in the upper end of said body 20 spill out through the said spill pipe. When this occurs, the upper outlet valve and valve 45a are closed, and the washing solution and eluent feed valves 28a and 29a and valve 240 are opened. The time between the opening and closure of valve 45a controlled by the timer shall always be sufficient to enable all of the preset volume of liquid to be injected into the annular chamber 22 as has previously been pointed out in connection with the description of FIG. 2 of the drawings.

The rate of resin flow is set by selecting an appropriate combination of impulse frequence, impulse pressure and impulse volume. Injection of a given volume of liquid under a given pressure will repeatedly cause the displacement of the same given volume of resin. The falling resin level in the annular chamber 22 in the base 21 of column 2 automatically starts the loaded resin flowing from hopper 43 through pipe 44 to the foot of the column until the material again heaps up to a height at which it will block ofi the opening to pipe 44. Hopper 43 has associated therewith a photoelectric cell resin level detector 48 which is so arranged in a control system of a type known to the art that when the level of the material in hopper 43 falls to the plane of the cell so that the cell is exposed to light, the cell triggers ofi means to feed washed resin into hopper 43 from which it will be fed into the annular chamber 22 of column 2 during a further series of impulses in the manner described. The feed of the washed resin to hopper 43 is controlled by a valve 42 operated by the timer 10.

It will be observed that the installation of this invention is automatic, all operations thereof being controlled by conventional programmed systems and remote control arrangements known to those in this art. Instrumentation such as flow measurement devices and pressure recorders may also be provided as is known in the art. The operating cycles, column base dimensions, annular chamber and auxiliary tank capacities, and impelling fluid volumes, are all determined on the basis of their necessity to achieve the desired transfer conditions in accordance with the invention.

While we have hereinabove described and illustrated in the accompanying drawings an example of the manner in which our invention may be practiced, it will be apparent to those skilled in the art that many other fonns may be utilized. Hence it is intended to include all such modifications and variations of the invention within the scope of the appended claims.

What is claimed is:

l. The method of treating liquids and solid particles in an installatlon which comprises at least one substantially vertical tubular treatment column of such materials and a tubular casing enclosing the lower portion of said column and forming therewith an unobstructed tubular chamber for holding a mass of solid particles, comprising efiecting an accurate control of the volume of material passing upwardly through such column by accumulating a given mass of the solid particles in said chamber, and then rapidly injecting tangentially into such chamber above such mass of solid particles a given volume of liquid under a given pressure to efiect a forward upward movement of said given volume of the material in such column, said injection of said given volume of liquid under said given pressure being repeated at intermittent intervals to efiect an intennittent forward motion of given volumes of the material in such column, said liquid being supplied from an exterior source thereof, and such supply being controlled by liquid measuring means located externally of said unobstructed chamber and constructed and arranged to measure the volume of liquid to be injected into said unobstructed chamber and to interrupt the flow of liquid from said source thereof on each measured given volume thereof.

2. The method defined in claim 1, in which said give volume of liquid is measured by collecting the same in a liquid collecting chamber, externally of said unobstructed chamber, and is injected thereinto by applying to the collected liquid compressed gas of a given pressure.

3. The method defined in claim 1, including the step of supplying the solid particles by gravity into said unobstructed chamber until the mass thereof reaches a given level below the place of tangential injection of the liquid into said chamber, and in which said given volume of liquid is measured by collecting the liquid in a liquid collecting chamber at a place exteriorly of the unobstructed chamber, and the measured given volume of liquid is then rapidly injected from such exterior place of collection thereof into the chamber by compressed gas of given pressure.

4. An installation for treating liquids and solid particles,

comprisin a tubulariy-shaped column providin a cylindrical chamber or a bed 0 the solid particles, a tubu ar casing enclosing the lower portion of said column and forming with the latter an unobstructed tubular chamber for holding a mass of solid particles, first means for periodically supplying a given volume of solid particles to said unobstructed chamber, and second means for rapidly injecting tangentially into such chamber above the mass of particles therein a given volume of liquid under a pressure to efiect a forward upward movement of a given volume of the material in such column, said second means being constructed and arranged to repeat at intermittent intervals the injection of a constant given volume of liquid under constant given pressure to effect an intermittent for ward motion of given volumes of the material in said column, and said second means including means exteriorly of said unobstructed chamber for supplying said liquid, liquid measuring means located externally of said unobstructed chamber for measuring the volume of liquid to be injected into said unobstructed chamber, and means controlled by said liquid measuring means for interrupting the supply of liquid by said supply means thereof on each measured given volume thereof.

5. An installation as defined in claim 4, in which said measuring means includes a liquid collection chamber located exteriorly of said unobstructed chamber and communicating with the latter and with said supply means, said controlled means being constructed and arranged to be responsive to the accumulation of liquid in said collection chamber to terminate the flow of liquid thereto by said supply means when said given volume is collected in said collection chamber, and means for feeding compressed gas under a given pressure into said collection chamber against the volume of liquid collected therein.

6. A installation as defined in claim 4, in which said particle supplying means includes means for feeding the solid particles by gravity into said tubular chamber until the mass thereof reaches a given level below the place of tangential injection of the liquid into said chamber, said particle supplying means being constructed and arranged to so feed the solid particles into said chamber in intervals between the intermittent operation of said second means. 

2. The method defined in claim 1, in which said given volume of liquid is measured by collecting the same in a liquid collecting chamber externally of said unobstructed chamber, and is injected thereinto by applying to the collected liquid compressed gas of a given pressure.
 3. The method defined in claim 1, including the step of supplying the solid particles by gravity into said unobstructed chamber until the mass thereof reaches a given level below the place of tangential injection of the liquid into said chamber, and in which said given volume of liquid is measured by collecting the liquid in a liquid collecting chamber at a place exteriorly of the unobstructed chamber, and the measured given volume of liquid is then rapidly injected from such exterior place of collection thereof into the chamber by compressed gas of given pressure.
 4. An installation for treating liquids and solid particles, comprising a tubularly-shaped column providing a cylindrical chamber for a bed of the solid particles, a tubular casing enclosing the lower portion of said column and forming with the latter an unobstructed tubular chamber for holding a mass of solid particles, first means for periodically supplying a given volume of solid particles to said unobstructed chamber, and second means for rapidly injecting tangentially into such chamber above the mass of particles therein a given volume of liquid under a given pressure to effect a forward upward movement of a given volume of the material in such column, said second means being constructed and arranged to repeat at intermittent intervals the injection of a constant given volume of liquid under constant given pressure to effect an intermittent forward motion of given volumes of the material in said column, and said second means including means exteRiorly of said unobstructed chamber for supplying said liquid, liquid measuring means located externally of said unobstructed chamber for measuring the volume of liquid to be injected into said unobstructed chamber, and means controlled by said liquid measuring means for interrupting the supply of liquid by said supply means thereof on each measured given volume thereof.
 5. An installation as defined in claim 4, in which said measuring means includes a liquid collection chamber located exteriorly of said unobstructed chamber and communicating with the latter and with said supply means, said controlled means being constructed and arranged to be responsive to the accumulation of liquid in said collection chamber to terminate the flow of liquid thereto by said supply means when said given volume is collected in said collection chamber, and means for feeding compressed gas under a given pressure into said collection chamber against the volume of liquid collected therein.
 6. An installation as defined in claim 4, in which said particle supplying means includes means for feeding the solid particles by gravity into said tubular chamber until the mass thereof reaches a given level below the place of tangential injection of the liquid into said chamber, said particle supplying means being constructed and arranged to so feed the solid particles into said chamber in intervals between the intermittent operation of said second means. 